1、Designation:D657221Standard Test Methods forDetermining Dispersive Characteristics of Clayey Soils bythe Crumb Test1This standard is issued under the fixed designation D6572;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of
2、 last revision.A number in parentheses indicates the year of last reapproval.Asuperscript epsilon()indicates an editorial change since the last revision or reapproval.1.Scope*1.1 Two test methods are provided to give a qualitativeindication of the natural dispersive characteristics of clayeysoils:Me
3、thod A and Method B.1.1.1 Method AProcedure for Natural Soil Crumbs de-scribed in 10.1.1.1.2 Method BProcedure for Remolded Soil Crumbsdescribed in 10.2.1.2 The crumb test,while a good,quick indication ofdispersive soil,should usually be run in conjunction with apinhole test and a double hydrometer
4、test,Test MethodsD4647/D4647M and D4221,respectively.Since this testmethod may not identify all dispersive clay soils,other testssuch as,pinhole dispersion(Test Methods D4647/D4647M),double hydrometer(Test Method D4221)and the analysis ofpore water extraction(Test Methods D4542)may be performedindiv
5、idually or used together to help verify dispersion.1.3 The crumb test has some limitations in its usefulness asan indicator of dispersive soil.Adispersive soil may sometimesgive a non-dispersive reaction in the crumb test.Soils contain-ing kaolinite with known field dispersion problems,haveshown non
6、-dispersive reactions in the crumb test(1).2However,if the crumb test indicates dispersion,the soil isprobably dispersive.1.4 These test methods are applicable only to soils wherethe position of the plasticity index versus liquid limit plots(Test Methods D4318)falls on or above the“A”line(PracticeD2
7、487)and more than 12%of the soil fraction is finer than2-m as determined in accordance with Test Method D7928.1.5 Oven-dried soil should not be used to prepare crumb testspecimens,as irreversible changes could occur to the soilpore-water physicochemical properties responsible for disper-sion(2).NOTE
8、1In some cases,the results of the pinhole,crumb,anddouble-hydrometer test methods may disagree.The crumb test is a betterindicator of dispersive soils than of non-dispersive soils(3).1.6 UnitsThe values stated in SI units are to be regardedas standard.No other units of measurement are included in th
9、isstandard.1.7 All observed and calculated values shall conform to theguidelines for significant digits and rounding established inPractice D6026.1.7.1 The procedures used to specify how data are collected/recorded or calculated in this standard are regarded as theindustry standard.In addition,they
10、are representative of thesignificant digits that generally should be retained.The proce-dures used do not consider material variation,purpose forobtaining the data,special purpose studies,or any consider-ations for the users objectives;and it is common practice toincrease or reduce significant digit
11、s of reported data to becommensurate with these considerations.It is beyond the scopeof this standard to consider significant digits used in analyticalmethods for engineering design.1.8 This standard does not purport to address all of thesafety concerns,if any,associated with its use.It is therespon
12、sibility of the user of this standard to establish appro-priate safety,health,and environmental practices and deter-mine the applicability of regulatory limitations prior to use.1.9 This international standard was developed in accor-dance with internationally recognized principles on standard-izatio
13、n established in the Decision on Principles for theDevelopment of International Standards,Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade(TBT)Committee.2.Referenced Documents2.1 ASTM Standards:3D653 Terminology Relating to Soil,Rock,and ContainedFluidsD1
14、193 Specification for Reagent Water1These test methods are under the jurisdiction ofASTM Committee D18 on Soiland Rock and are the direct responsibility of Subcommittee D18.06 on Physical-Chemical Interactions of Soil and RockCurrent edition approved May 1,2021.Published May 2021.Originallyapproved
15、in 2000.Last previous edition approved in 2020 as D6572 20.DOI:10.1520/D6572-21.2The boldface numbers in parentheses refer to the list of references at the end ofthis standard.3For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For An
16、nual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.*A Summary of Changes section appears at the end of this standardCopyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United StatesThis international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards,Guides and
